1 files changed, 38 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/repeat_vec_with_capacity.rs b/src/tools/clippy/tests/ui/repeat_vec_with_capacity.rs
new file mode 100644
index 000000000..659f2a395
--- /dev/null
+++ b/src/tools/clippy/tests/ui/repeat_vec_with_capacity.rs
@@ -0,0 +1,38 @@
+#![warn(clippy::repeat_vec_with_capacity)]
+
+fn main() {
+    {
+        vec![Vec::<()>::with_capacity(42); 123];
+        //~^ ERROR: repeating `Vec::with_capacity` using `vec![x; n]`, which does not retain capacity
+    }
+
+    {
+        let n = 123;
+        vec![Vec::<()>::with_capacity(42); n];
+        //~^ ERROR: repeating `Vec::with_capacity` using `vec![x; n]`, which does not retain capacity
+    }
+
+    {
+        macro_rules! from_macro {
+            ($x:expr) => {
+                vec![$x; 123];
+            };
+        }
+        // vec expansion is from another macro, don't lint
+        from_macro!(Vec::<()>::with_capacity(42));
+    }
+
+    {
+        std::iter::repeat(Vec::<()>::with_capacity(42));
+        //~^ ERROR: repeating `Vec::with_capacity` using `iter::repeat`, which does not retain capacity
+    }
+
+    {
+        macro_rules! from_macro {
+            ($x:expr) => {
+                std::iter::repeat($x)
+            };
+        }
+        from_macro!(Vec::<()>::with_capacity(42));
+    }
+}